The anticlinal of Bresle establishes with the anticlinal of Penly two only examples of folds anticlinaux marked well on the coast of the Coast of Alabaster. It is here the western side of the anticlinal of Bresle that we are going to travel. Coats at the heart of the fold appear on the platier lining the shingle beach of Tréport, it is chalks in big ammonites under marls Malling Street (in the anticlinal of Penly, coats older are observed). By moving towards him W, we go back up the coats of upper and average Turonien. In Mesnil-valley, we reach terminal Turonien with the bentonite Lewes and the flint Mesnil-valley which is stacked to him. If we want to reach the contact Turonien / Coniacien, it will be necessary to walk until the accesses of the beach of Criel. The permanent mark in the cliff is exactly the bentonite Lewes. She highlights undulations of type "hillocks and basins" " of low amplitude, but which find themselves on long distances beyond the synclinal axis of Criel. The anticlinal of Bresle owes it began to form in Turonien and to have heightened the sedimentary bottom, as shown by the condensation of the series, the exacerbation of hard-grounds (hard-grounds Seas) and the reduction to ghosts of marls Southerham, Caburn and Bridgewick.
Seen eastward since The Terraces of Tréport. On other bank of Bresle, in the distant, the sea sea resort.
The estuary of the Somme with its tidal reservoirs, its mollières and its salty meadows puts an end in the long run wall of the Country of Callus and its continuation picard. It is not that in the Course White-nose that the chalk will reappear on a short distance. The cliff gives way to low ground at the level of Onival-sur-Mer, locality dependent on the municipality of Ault. A fold anticlinal, centred on Tréport, made that by leaving from the sea beach we travel the side is. We so go back up the stratigraphical series of lower Turonien until lower Coniacien than we achieve the staircase of the Wood of Cise. Between the Wood of Cise and Ault, the pendage almost nobody allows to affect higher stratigraphical horizons. The rather high cliff allows however to kiss the totality of Coniacien. At the level of the hinge anticlinale of Tréport, he had to exist in upper Turonien a zone at the bottom heightened because he develops very marked hard-grounds (the hard-grounds of Seas) responsible for a condensation of the series and for the disappearance of certain levels-marks there.
Partial consequence of the frost and\or the drought, the chalk undergoes constraints which widen his cracks and which weaken his resistance. In this time, the big collapses of the chalky cliffs are particularly frequent, in France as in "deceptive" Albion (yes, Albion because of his white cliffs). MailOnline, in an article of March 29th, 2012, present an enormous collapse having taken place in him E of Dover in the said place Crab Bay. The cliffs of Dover are famous, of course for their beauty, but also in the history of the geology because the pioneers of this science were widely interested in it. Langdon Stairs, a staircase in zigzag, allows to reach the sea and to realize a cup going of Turonien lower than average Coniacien, often presented as a stratigraphical reference. The collapse of Crab Bay would have made no victim, but he reminds to each that the closeness of the cliff is dangerous.
Extract of John McLellan's air cliché, accompanying the quoted article
Dumped (B. Hoyez) cliffs in him E of Dover grip since the ferry, before the collapse
Swelling of the zone of the collapse, before the event (in May 30th, 2010) - Dumped B. Hoyez
We can compare clichés, before and after the collapse. Thanks to Yves Lepage for the information.
The mount Jolibois, the highest point of the coast to 106 m, seen since the beach of Criel
It is the excursionrather long and physically painful , but that offers the advantage to travel and to affect almost the completeness of Turonien. She is situated between two axes of folds:
The axis anticlinal of Penly who crosses in approximately 500 m east of the power plant,
The synclinal axis of Criel which passes at the level of the nautical circle of Criel.
We can say that she is symmetric of the one who develops between the terminal ferry of Dieppe and the power plant of Penly, that is on the western side of the anticlinal of Penly. The series is however slightly more condensed by the development of the facies Chalk Rock, that is of hardgrounds appearing below and over the bentonite Southerham. On the other hand, the last interval of Turonien (T8) is more thick him. We see developing also, towards the summit of Turonien (T7-T8), modest undulations of the sea bed which can give rise to coats in bevel. Under the bentonite Lewes, tubular flints and thick tabular flints are resumed in mass origin of which paléosismique is likelyslidings . These phenomena, already present on the western side of the anticlinal of Penly, are much better expressed here. Lower Coniacien cannot be affected between Penly and the beach of Criel, but we can follow him correctly in the high or average cliff. Hardgrounds navigations are underlined well in the landscape, which is not the case for the superior hardgrounds (Cliffe, Hope Gap, Beeding). Both marl Shoreham follows itself with more or less of neatness. The marl Shoreham 1 is preceded by a rather thick episode of expanded flints recovering chalks larded of sheet-flints. It is, undoubtedly, the expression of a paléoséisme effects of which were described in other sectors. To affect lower Coniacien, it is necessary to go east of the beach of Criel and the automobile parking lot, on the esplanade of the nautical center, where the basal coats of Coniacien are observable permanently over the sea level. The phenomena paléosismiques infra-Hope Gap is particularly very visible there.
Students from Brest in the discovery of the cliffs of chalk
On Sunday, February 19th, 2012, a beautiful day brightened up to discover the cliffs of Saint-Jouin-Bruneval and Etretat. The assocation PATEL (Protection and Town and country planning and the Littoral Environment) gathering all the students of the Master's degree Sciences of the Sea and the Coast mention Evaluates and Management of the Littoral Environment of the European University Institute of the Sea (Brest) came to learn about the geology of the chalk and to be amazed at landscapes universally known. This excursion, under the direction of Yves Lepage and of Bernard Hoyez took place from 12 am till 6 pm, with a historic interlude in front of a warm drink offered by the municipality of Saint-Jouin-Bruneval which we thank for its welcome.
The group of students during the excursion. Dumped Yves Lepage
In the of the valleuse Boucherot, we observe the completeness of Norman Cénomanien. No other regional cup allows to see the totality of the floor. The indicated levels-marks are clarified in other pages of the site. We notice a water-bearing level, realized by the head of stalactites. This level is under big underlying black flints in hardgrounds Bruneval, situation identical to that in N of the valleuse of Bruneval.
Here is a slide show commented, presented to pupils of high school within the framework of the conferences "Seeds of Science" organized by the U.F.R.S.T. of the University of Havre. His duration is of 15 minutes. We approach some peculiarities of the chalk and the history of cliffs there.
This excursion allows to reach the heart of the anticlinal of Penly and to discover coats older dated the base of average Turonien. Valleuse of the Priest, in Was born Belleville-sur-mer is of an easy access with restricted spaces of parking lot. The cliff of Crocq, dominated by the hamlet of Berneval, is impressive with its 97 meters. In a place, the set of Turonien can be kissed at a glance. As the cup approaches the hinge anticlinale, pendages diminishes and the swept stratigraphical interval is relatively short. The vast sandy beach of Martinmas allows to devote to all the seaside, halieutic and sports activities. To avoid being taken by the tide, the return can be made by the GR 21 which crosses the tray. For the detail, see here.
It is the most demonstrative cup of Turonien of the Country of Callus, to complete with that of Volcanic hills in Dieppe and that of Belleville to the power plant of Penly. The thicknesses are strongest there. The levels bentonitiques are any presents. This cup can serve as reference to compare with the facies of Etretat, Senneville-sur-mer, Penly-Tocqueville or Mesnil-beach. You will find more detail here.
A sunny day, why not to stroll on the quays of the pond of Dieppe, to cross the bascule bridge and to climb on Notre-Dame-du-Bonsecours to admire the panorama? From there, you follow the GR 21 which leads you to the beach of Volcanic hills, to 2,5 km, through the top of the cliff. For the return, made a little of geology by staying this time at the foot of the cliff. The cup is a historic great classic which will make you cross lower Coniacien. Do not hesitate to break the pebble in the excavation to him E of the entrance of the terminal ferry, you some should find beautiful sample of Micraster there. A small guide in image can be useful for you.